Direct drive for a printing-press cylinder

ABSTRACT

The invention relates to an electromotive direct drive for one cylinder ( 1 ) of a printing press, which cylinder ( 1 ) is held in a connecting construction ( 3 ) with a journal ( 2 ) via a roller bearing ( 4 ), a rotor ( 6.1 ) of an electric motor ( 6 ) being connected fixedly in terms of rotation to the journal ( 2 ), and a stator ( 6.2 ) being connected to the connecting construction ( 3 ). 
     This drive is distinguished by the fact that the rotor ( 6.1 ) is connected to an end side of the roller bearing ( 4 ), and the stator ( 6.2 ) is accommodated by a housing ( 9 ) which can be fastened to the connecting construction ( 3 ) via a bearing housing ( 5 ). 
     The advantage of this direct drive according to the invention lies in the fact that the drive and the bearing are combined as a captive, preassembled structural unit which can be handled in a simple manner.

FIELD OF THE INVENTION

The invention relates to an electromotive direct drive for one cylinderof a printing press, which cylinder is held in a connecting constructionwith a journal via a roller bearing, a rotor of an electric motor beingconnected fixedly in terms of rotation to the journal, and a statorbeing connected to the connecting construction.

BACKGROUND OF THE INVENTION

In the past, printing units of printing presses have been driven by amain drive which distributes its drive power to the individual units ofa printing press via a mechanical line shaft. The printing units areconnected and coupled to one another by said mechanical line shaft insuch a way that their synchronized running with respect to one anotheris also possible. In order to realize this, however, a complexmechanical system is necessary with a large number of differentcomponents such as gear mechanisms and clutches. The weak points whichresult from this, such as transmission errors on account of yielding ofmechanical transmission members, play, elasticity and additional largeinertial masses, impair the printed image, however.

Attempts have been made to eliminate this deficiency by a separate,electromotive drive being assigned to every printing unit or itscylinder. A separate printing drive of this type, which is also called adirect drive, for one cylinder of a printing press is already known fromDE 41 38 479 C3. Said drive makes it possible that a drive train whichis free of play, low in inertial mass and mechanically rigid can beconstructed for every cylinder or every roll of a printing unit. Themasses which are to be moved are connected rigidly and fixedly to therotor of the driving electric motor directly, with the preclusion ofelasticity, yielding and play, the associated stator likewise beingconnected to a stationary wall, for example a printing press wall, in amanner which is free of elasticity and play. As can be gathered fromFIG. 7 of this prior publication, a cylinder of a printing unit isprovided at one end side with a journal of reduced diameter. At its endwhich faces the cylinder, said journal is held by a roller bearing. Arotor of an electric motor is pushed onto the journal in a manner whichis spaced apart from said roller bearing, the associated stator of saidelectric motor being held by an adjustment wall of the printing press. Adisadvantage of this arrangement is that it requires relatively highexpenditure on assembly, because the bearing which holds the journal andthe driving electric motor do not form a unit which is ready forinstallation.

This form of direct drive is also known from EP 1 277 575 A1. As shownby the associated FIGS. 31, 32 and 33 of this prior publication, thejournal of a cylinder of a printing press is held in a housing via abearing point. In turn, this bearing point is adjoined by an electricmotor, the rotor of which is pushed onto the journal and the stator ofwhich is accommodated by a housing which is connected to a frame wall.The abovedescribed disadvantages are also apparent here, that is to saythe electric motor of the direct drive and the associated bearing of thejournal do not form a unit which is ready for installation.

SUMMARY OF THE INVENTION

Proceeding from the disadvantages of the prior art, the invention isbased on the object of developing an electromotive direct drive forcylinders of a printing press in such a way that said direct drive isconfigured for handling which is amenable to assembly, that is to sayeasy.

According to the invention, this object is achieved by the rotor beingconnected to an end side of the roller bearing, and the stator beingaccommodated by a housing which can be fastened to the connectingconstruction via a bearing housing.

The decisive advantage of the direct drive which is configured accordingto the invention lies in the fact that a captive structural unit whichcombines the electric motor and the bearing is formed, which structuralunit can be attached by the end user in a simple manner merely byfastening it into its connecting construction. This is advantageous, inparticular, as the rotor and the stator of the electric motor cannotchange their operating position with respect to one another as a resultof the configuration according to the invention, because they areconnected fixedly to other constituent parts of the structural unit.This is of significance as great forces can occur between the two onaccount of permanent magnets. The other advantages which are known perse of a direct drive for driving one cylinder of a printing press arepreserved. Therefore, a drive train which is free of play, low ininertial mass and mechanically rigid can be constructed for everycylinder or for every press roll, which drive train is additionallycombined to form a captive structural unit. In this way, the printingquality can be improved, as the masses which are to be moved areconnected rigidly and fixedly to the rotor of the driving electric motordirectly, with the preclusion of elasticity, yielding and play. There isno need at this point to address further advantages of direct drives inprinting presses, as they are known to the person skilled in the art andare also shown in detail, for example, in DE 41 38 479 C3.

Further advantageous refinements of the invention are described below.

In one development of the invention, there is provision for the bearinghousing to be held concentrically by a an accommodation hole of theconnecting construction. This has the advantage that installation spacecan thus be saved in the axial direction.

According to a further additional feature, the rotor is to cover an endside of the journal at least partially in the radially inward direction.It is ensured in this way that the structural unit which comprises theelectric motor and the bearing can be fastened to the journal of thecylinder in a simple manner.

According to a further additional feature, the roller bearing is to beconfigured as a cylindrical roller bearing, a tapered roller bearing oran angular contact ball bearing.

There is provision for an outer raceway of the roller bearing to beformed by an outer ring or by the bearing housing itself. In the lattercase, the structural unit is reduced by one constituent part, with theresult that said structural unit is designed even more simply.

It is apparent that the outer raceway of the roller bearing is offseteccentrically with respect to an axis of the receptacle hole of theconnecting construction. It is possible in this way for the rotationalaxis of the cylinder to be adjustable, in that the outer raceway of theroller bearing can be deflected eccentrically within the connectingconstruction. The cylinder can thus be adjusted or positioned withrespect to a further cylinder by rotation of the complete unit.

In one advantageous development of the invention, a measuring apparatusfor determining the rotational angle of the cylinder is to be arrangedon said cylinder for achieving synchronism with other cylinders of theprinting press. In the context of the invention, this is to beunderstood as a fixed direct connection between the cylinder and themeasuring apparatus, which connection avoids measuring errors ofprevious systems which are connected to the cylinder via couplingelements.

It is apparent that a sensor is arranged in the bearing housing, whichsensor is operatively connected to an encoded measuring ring which isarranged on the journal of the cylinder, the sensor signals which aredetected being supplied to a control device for adjusting advanced orretarded running.

In this way, precise synchronism of a plurality of cylinders of aprinting press can be achieved, as corrections to the advanced orretarded running of individual cylinders can be performed by the controldevice in a simple manner. Regulating systems of this type in theprinting industry are already known per se and have already beendescribed, for example, in DE 43 22 744 C2, DE 197 14 402 A1, DE 197 16943 A1 and DE 197 54 323 A1. In the context of the invention, theadvantage lies in the fact that this regulating device which is knownper se for setting the synchronism of a plurality of cylinders is aninherent constituent part of the structural unit according to theinvention.

Finally, there is provision for the measuring ring to be a separatecomponent or to be formed by an axial extension of an inner ring of theroller bearing.

The invention will be described in greater detail using the followingexemplary embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a longitudinal section through a direct drive according tothe invention of one cylinder of a printing press, and

FIG. 2 shows a perspective illustration of the direct drive according toFIG. 1, in a partially sectioned view.

DETAILED DESCRIPTION OF THE DRAWINGS

The electromotive direct drive which is shown in FIGS. 1 and 2 for aprinting press exhibits a cylinder 1 which is continued at one end by ajournal 2 of reduced diameter. Said journal 2 is held via a rollerbearing 4 in a connecting construction 3, for example a frame wall. Saidroller bearing 4 is configured as a double-row floating cylindricalroller bearing which is pretensioned without play, and has an outer ring4.1 and an inner ring 4.2, between which cylindrical rollers 4.4 whichare guided in cages 4.3 roll on associated raceways. The bearing 4 isheld concentrically by a bearing housing 5, the bearing housing 5 inturn being held concentrically by the receptacle hole 3.1 of connectingconstruction 3.

A further part of the direct drive is an electric motor 6, the bowl-likerotor 6.1 of which covers the end side of the journal 2 partially in theradial direction and is fixed to said end side with the aid of fasteningscrews 7. At the same time, the rotor 6.1 is connected via furtherfastening screws 8 to the end side of the inner ring 4.2 of the rollerbearing 4. The stator 6.2 is accommodated by a housing 9, the base 9.1of said housing 9, which extends in the radial direction, beingcontinued by an inner and an outer flange 9.2, 9.3 which extend in thedirection of the axis 10. The stator 6.2 is fitted fixedly in terms ofrotation to the inner flange 9.2 of the housing 9 in any desired manner.The housing 9 is connected via fastening screws 11 to the bearinghousing 5, the latter in turn being surrounded concentrically by theconnecting construction 3 and being connected fixedly to the latter viafurther fastening screws 12. In this way, a structural unit is formedwhich comprises the roller bearing 4, the bearing housing 5, the rotor6.1, the stator 6.2 and the housing 9, and which is held together by thefastening screws 8 and 11. This has the advantage that the rotor 6.1 andthe stator 6.2 cannot change their position with respect to one another,that is to say the air gap 6.3 which is formed between the two is alwaysconstant. The assembled structural unit which is stable and adapted tothe requirements of a printing press manufacturer is delivered to thelatter, who need only introduce it into his construction in a simplemanner with the aid of fastening screws 7 and 12.

As can be seen further from the abovementioned figures, a measuringsystem is also part of the direct drive, it being possible to sense therotational angles of the cylinder 1 with the aid of said measuringsystem. Said measuring system comprises a sensor 13 which is operativelyconnected to an encoded measuring ring 14. The sensor 13 is held by areceptacle hole of an extension 5.1 of the bearing housing 5 and isarranged spaced apart in the radial direction from the measuring ring14, the latter being positioned on the journal 2 next to the bearinginner ring 4.2. The encoding marks of the measuring ring 14, which arespaced apart from one another uniformly in the circumferentialdirection, are scanned by the sensor 13, and the sensor signals aresupplied to a control device, for example a microcomputer, whichdetermines the corresponding rotational angles of the cylinder 1. Saidrotational angles of the cylinder 1 are then compared with rotationalangles of other cylinders of the printing press and corrected in such away that the rotational speed is maintained, increased or decreased. Inthis way, synchronous running of a plurality of cylinders of a printingpress can be realized in a simple manner. The advantage of thismeasuring arrangement lies in the fact that it is an inherentconstituent part of the assembled direct drive unit. Complicatedmeasuring arrangements which have to be attached from outside cantherefore be dispensed with. Possible sources of faults are alsoprecluded by the integration of the measuring arrangement into thedirect drive unit.

LIST OF DESIGNATIONS

-   1 Cylinder-   2 Journal-   3 Connecting construction-   3.1 Accommodation hole-   4 Roller bearing-   4.1 Outer ring-   4.2 Inner ring-   4.3 Cage-   4.4 Cylindrical roller-   5 Bearing housing-   5.1 Extension-   6 Electric motor-   6.1 Rotor-   6.2 Stator-   6.3 Air gap-   7 Fastening screw-   8 Fastening screw-   9 Housing-   9.1 Base-   9.2 Inner flange-   9.3 Outer flange-   10 Axis-   11 Fastening screw-   12 Fastening screw-   13 Sensor-   14 Measuring ring

1. An electromotive drive for a printing press cylinder having a journaland supported in a printing press housing, comprising: an electric motorhaving a stator and a rotor; a motor housing for containing the electricmotor; a roller bearing having an end face, wherein the roller bearingis configured to be fitted over the journal and to support the journalwithin the printing press housing; a bearing housing for containing theroller bearing and being configured to be affixed to the printing presshousing; wherein the roller bearing, rotor, stator, and motor housingare provided as a single unit that can be fitted to the journal so thatmost of the rotor does not extend axially along the journal; the statorbeing configured to be fixedly attached to the printing press housing,and the rotor fixedly attached to and extending beyond the end face ofthe roller bearing.
 2. The direct drive as claimed in claim 1, whereinthe rotor extends at least partially radially over an end face of thejournal.
 3. The direct drive as claimed in claim 1, wherein the rollerbearing is a cylindrical roller bearing.
 4. The direct drive as claimedin claim 1, wherein the roller bearing has an outer raceway that isformed by an outer ring or by the bearing housing.
 5. The direct driveas claimed in claim 4, wherein the outer raceway of the roller bearingis offset eccentrically with respect to an axis of a receptacle hole oflocated within the printing press housing.
 6. The direct drive asclaimed in claim 1, further comprising a measuring apparatus that isarranged on the cylinder for determining the rotational angle of thecylinder for enabling its synchronous operation with at least one otherprinting press cylinder.
 7. The direct drive as claimed in claim 1,further comprising a sensor arranged in the bearing housing and anencoded measuring ring that is configured to be arranged on the journal,said sensor being operatively connected to the encoded measuring ring,the sensor detecting signals which are used for adjusting the speed ofoperation of the cylinder.
 8. The direct drive as claimed in claim 7,wherein the measuring ring is formed as a separate component.
 9. Thedirect drive as claimed in claim 7, wherein the measuring ring is partof an axial extension of an inner ring of the roller bearing.
 10. Amodular cassette for providing electromotive drive to a printing presscylinder that is located within a printing press housing, the cylinderbeing supported by a journal, the modular cassette comprising: anelectric motor having a stator and a rotor, with a fixed air gaptherebetween; a motor housing for containing the electric motor; aroller bearing having an end face, wherein the roller bearing isconfigured to be fitted over the journal and to support the journal; abearing housing for containing the roller bearing and being configuredto be affixed to the housing of the printing press; wherein the rollerbearing, rotor, stator, and motor housing are a single unit that can befitted to the journal so that when the single unit is attached to aprinting press, the stator is fixedly attached to the printing presshousing, and the rotor fixedly attached to and axially extends beyondthe end face of the roller bearing and does not extend axially along thejournal.